The invention relates to a screening device for a heat exchanger of a vehicle.
German Patent 3,631,785 discloses a screening device for dividing an air duct into two subducts: one through which air flows and one through which water flows. With the screening device opened, cooling air can flow through the entire cross-section of the radiator. However, when the vehicle is operated on land, with the screening device completely closed, the flow of cooling air through the radiator is completely closed off. In this mode of operation, one of the subducts is blocked directly by a flap-type blind, which is arranged in front of the radiator, and abuts a partition wall. The flow through the second subduct, on the other hand, is blocked indirectly; that is, by a back pressure space bounded by the partition wall, a duct wall and a separate flap which screens off an overflow opening lying behind the radiator, between the partition wall and the duct wall.
The known division of the air duct is relatively expensive since the partition wall must pass straight through the radiator, and the additional flap requires its own drive and control. In addition, the overall arrangement of the screening device in the air duct requires a considerable amount of installation space, which is frequently unavailable.
Another, screening device of the generic type, which is arranged in a particularly compact air duct, is disclosed in German Offenlegungsschrift 3,836,374. This screening device consists of a single flap-type blind situated in a space-saving manner between a radiator and a fan. Since this flap-type blind completely covers the radiator, the flow of cooling air is completely blocked when the radiator blind is closed. In addition, in the open condition the flaps of the radiator blind, which lie opposite a fan cowl duct wall running obliquely towards the fan aperture, are oriented obliquely towards the fan aperture. As a result, the oblique flaps act as baffle surfaces and require only a small overall depth. However, because the duct wall runs a short distance behind the screening plane of the flap-type blind, the resistance of the radiator to through flow in the region of the oblique flaps is increased considerably. Despite the reduced overall depth of the oblique flaps, that heat-exchanger area of the radiator which is affected by them cannot be fully utilized, particularly during the flow of relative wind through it. If, on the other hand, the distance of the duct wall from the rear edges of the oblique flaps were increased, an undesired enlargement of the fan cowl would also result.
The object of the present invention is to provide a screening device of the generic type for a heat exchanger of a vehicle which is less expensive to construct, and at the same time is suitable for arrangement in a compact air duct.
This and other objects and advantages are achieved according to the invention, in which a flap type blind extends only to that portion of the air flow path adjacent the fan aperture, with a specially shaped lateral terminating flap which seals off air flow in the remainder of the air flow path. Since, according to the invention, all flaps belong to the screening device of the flap-type blind, a drive and a control are required only for the flap-type blind itself. In addition, because the flap-type blind must now only cover that region of the area of the heat exchanger through which air flows virtually in a straight line, only a minimum number of flaps is required.
For a common drive of all flaps of the flap-type blind, it is expedient if their rotational axes lie in a single plan. If the special flap forming the lateral termination of the flap-type blind is mounted on a rotational axis near its rear edge, the sealing wing of the adjacent flap can come to rest against the rear edge of the special flap, which is moved in the same direction but offset at an angle.
If, with the flap-type blind opened, the special flap lies obliquely to the inflow direction of the relative wind, it can have a rotating angle corresponding to that of the remaining flaps, a common drive thereby being further simplified. Moreover, optimum utilization of the construction space is possible if, with the flap-type blind in the open position, the leading edge of the special flap lies in the same plane with the leading edges of the remaining flaps. In this arrangement, the leading edges can extend almost as far as the exit are of the heat exchanger.
In order for the special flap to overlap with the adjacent flap (which corresponds to the remaining flaps), the special flap can be provided with an angled wing. The length of this wing, however, should be restricted to the dimension of the flap overlap since, with the flap-type blind opened, the leg protrudes into the overflow opening.
Because of its compact construction, the screening device according to the invention is highly suitable for arrangement as a radiator blind in cramped fan cowls of motor vehicles.
In addition, use on heat exchangers, such as those which are common in motor vehicles for heating or air conditioning, would however also be conceivable.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.